Method for producing lubricating oil



Patented May 25, 1937 Ulric B. Bray, Los Angeles, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corporation of, California No Drawing. Application March 7, 1932, Serial No. 597,419

19 Claims.

This inventionrelates to-a process for the production of lubricating oil. More specifically, it relates :to a process for the production of lubricating oil from crude oil containing asphalt and is a continuation in part of. my application,

Serial No. 466,189, filed July 7, 1930.

The value of oils. as lubricants depends,to a large extent, upontheir. viscosity-temperature susceptibility, thatxis, their rate of change in viscosity with a change in temperature. Superior lubricating oils exhibit a low viscosity temperature susceptibility. By careful selection of crude stock, lubricants can be produced which exhibit a low viscosity temperature susceptibility. Lubricants made from residuesof Pennsylvania parafiin base crude oil are of this class; however, the supply of this superior crude stock is limited and it, therefore, becomes necessary to obtain lubricants from other sources.

In the aforesaid application filed by me, I have. shown that the lubricating oil components of most crude, oil contain. asphalt or asphalt and Wax and are of a mixedzcharacter. Some of the constituents present have a high viscosity temperature susceptibility and in this; respect resemble the ordinary commercial type of lubricating oil made from distillates of asphalt base crude oil. Furthermore, I have alsopointed out" that most asphalt base crude oils contain-certain.

heavy lubricating-oil components which'upon isolation from the crude oil exhibit a low viscosity temperature susceptibility. In ordinary refinery practice these heavy lubricating oil components of the crude-oil are left in'the asphalt and do not find'their way into finished lubricants. In case they are distilled overhead they lose their valuable viscosity characteristics and become highly susceptible to a change in viscosity with achange in temperature. This impairment inthe viscosity characteristics of the heavy oils, appears to become even more pronounced when the distillation is carried out in the presence of asphalt.

Furthermore, in. order to evaluate oilsaccord ing to their temperature viscosity susceptibility characteristica. lubricants which exhibit a low temperature viscosity susceptibility, such as Pennsylvania paraflin base lubricating oils, are described as having paraifin base characteristics; lubricating oils; produced from distillates: of asphaltic crude oil by the ordinary com- 5 mercial. processes and which exhibit a high temperature viscosity susceptibility are described as having 0% paraflin base characteristics, and lubricating oils which-exhibit temperature viscosity susceptibility characteristics intermediate between- Pennsylvania lubricating oil and lubricating oil produced fromv asphalt distillates are evaluated according to the extent by which their temperature viscosity susceptibilities resemble the Pennsylvania parafiln base lubricating oil.

This is. best. shown. by the. ratioof the intercepts of the viscosity temperature curves of the paraffin base lubricating oil and the lubricating oil produced from asphaltic oil distillate with the oil having viscosity temperature susceptibilities 20 intermediate between the two foregoing standard comparison oils.

I have also shown that crude oils which contain asphalt can be distilled to acertain point beyond which any further distillation will im- 25 pair the viscosity temperature characteristicsof the heavy oils in the asphaltic residue. Furthermore, I have .shown that by distillingan asphaltic crude oil-to a point below which anyimpairment in the viscosity temperature characteristics of. the oil in the residue takes place and then separating the oil and asphalt in the residueby the use of certain solvents that I am able to obtain an oil which exhibits a low viscosity temperature susceptibility.

Furthermore, in the aforementioned application filed by me it was pointedout that oils which have been deprived of their asphalt content can be distilled to a point at which heavier overheadfractions are obtained without any substantial impairment of the viscosity temperature susceptibilityof the heavy oils in the still'residue than is possibl'e where the distillation of the oil is carried out in the presence of the asphalt.

Tables 1 and 2 following, are illustrative of this By referring to Table 2, it is also seen that fact: the still bottoms have high parafiin base char- TABLE 1 5 Steam distillation of Santa Fe Springs crude topped to 106 seconds ozscoszty on stream-72% overhead Percent Percent Overhead viscosities head of h d Still Over- Percent par- 10 out NO topped tam head afiin base crude 28 original FD grav. characterpercent crude A. P. I. 100F 130 F. 150 F. 210 F. 250 F. 300 F. 1st1cs residuum TABLE 2 Steam distillation of extracted oil obtained from Santa Fe Springs crude topped to 106 seconds viscosity on stream-72% overhead Overhead viscosities, sleeonds Saybolt universe. P5531 Percent over- Percent Max. Over- Percent partNO head head of topped overhead temp. head afiin base Still crude .28 perof original still 0 grav. characterischarge cent residuum crude F. A. P. I. 0 F. 0 F 1505-F 5 F 0 F tics Tests on samples of bottoms taken at end of above cuts P t Viscosities, seconds Saybolt universal Percent amen Percent Percent 21 bottoms Max. p r bottoms bottoms Grav. affin base At of out of still 33358 of original gg ff' A.P.I. character.

charge residuumo crude 0F. 100 F. 130 F. 150 F. 210 F. 250 F. 300 F. istics 50 Raw material 28. 0 21. 5 57 1 90 92. 2 25. 0 500 21. 1 4

I I 5 Table 1 shows the efiect of distilling 011 in the acterlstics. The absence of the asphalt during presence of asphalt. Temperatures above 600 the distillation results in the preservation of the F. are shown to be highly injurious to the paraffin low viscosity temperature susceptibilities posbase characteristics of the overhead oil. sessed by the heavy oils present in the still Table 2 shows the effect of distilling oil which residue. has been deprived of its asphaltic content by 801- It is, therefore, an object of my present invenvent extraction. From the data given in this tion to produce lubricating oil from oil containing table it is obvious that no substantial lowering asphalt by separating the asphalt from the oil of the parafiin base characteristics of the overand .then separating the oil by distillation into head fractions has taken place at 700 F. Furits light and heavy components.

thermore, it is safe to say that the distillation of the asphalt free oil can be continued to a temperature of 750 F. without any substantial impairment of the parafiin base characteristics of the overhead oil.

- 19.91% isobutane and 1.17%

lubricating oilfractions by fractionaldistillation.

It is another object of my invention to produce lubricating oil from .oil; containing asphalt by separating the asphalt from the oil by the aid of a solvent and then to distill the substantially asphalt free oil, into a distillate anda residuum, interrupting the distillation at a point below which there is any substantial impairment of the temperature viscosity susceptibility of the residual oil.

As means of separating the asphalt from the oil, I may employ solvents or chemicals. Thus, I may employ such solvents as alcohol, mixtures of alcohol and ether, acetone or volatile hydrocarbon solvents, such as casinghead gasoline and light naphthas. I find, however, that the process is best carried out by the use of hydrocarbons which are normally in the vapor state at atmospheric pressure and temperature. Such hydrocarbons include propane, isobutane, butane, ethane, methane and mixtures thereof. These may be obtained by rectification of casinghead gasoline by the so-called stabilizing method, now conventional in the natural gas industry, they are the overhead thus obtained. They are liquefied by compression and cooling in the conventional manner and drawn off into pressure chambers where they are maintained in a liquid state until they are used. A typical analysis of such a fraction is 6.72% ethane, 72.20% propane, normal butane. The pressure necessary to maintain such a fraction. in the liquid state is approximately 125 pounds per square inch at 73 F. In future discussions such a solvent will be referred to as propane. It will be understood, however, that the term propane will cover other light volatile hydrocarbon mixtures in which the percentage of propane predominates similar to the one shown above.

By extracting the asphaltic oil with a solvent capable of separating the asphalt from the oil and then distilling the oil to remove the light fractions, I am able to obtain an asphalt free heavy oil residue having a low viscosity temperature susceptibility which may be employed as a superior lubricant. The removal of the asphalt prior to the distillation permits the separation of heavier oil fractions as distillates from the asphalt free oil without an impairment of viscosity characteristics of the oil remaining in the still.

In carrying out my invention other means may be employed to separate the asphalt from the oil prior to the distillation step. asphaltic oil may first be treated with sulphuric acid to separate the asphalt present after which the asphalt free oil may be distilled to separate the light oil fractions present away from the residual oil which possesses a low viscosity temperature susceptibility. Other chemicals may also be employed to separate the asphalt from the oil, as for example, the metallic halides. The oil containing asphalt is treated with a metallic halide at a temperature sufficiently high to coagulate the asphalt present. The coagulated asphalt is allowed to settle out and the asphalt free oil is decanted away from the coagulated asphalt and distilled to remove the light oil fractions from the residual oil.

In some cases it is desirable to employ both solvent, extraction and chemical means to separate the asphalt from the oil prior to the distillation of the oil for the separation of the light oil fractions from the valuable residual lubricants.

Thus the Thus I may first commingle the asphaltic oil, with a light, hydrocarbon solvent, such as propane, to. cause the majorv portion of the asphalt to precipitate out. After removing the precipitated asphalt. from the light hydrocarbon solution of oil the latter may be further purified to remove any remaining undesirable bodies by treatment with sulfuric acid. The asphalt free and acid treated oil may thenbe distilled to remove the light hydrocarbon solvent and' oil fractions from the heavy oils present which are characterized. by exhibiting a low viscosity temperature susceptibility.

In my prior case, Serial No. 466,189, filed July- '7, 1930, as has already been explained, I first topped the oil to a definite point for the removal of the light fractions after which the asphaltic residue was extracted with a light liquid hydrocarbon, such as liquid propane, to separate the asphalt from the oil. Thetopping operation was discontinued at the point below which any substantial impairment in the viscosity temperature characteristics had taken place. In most cases this limiting point in the topping operation is attained when the still temperature reaches 650 F.; or where the viscosity of, the oil on stream has reached approximately 500 seconds Saybolt Universal at F. In my present method of operation in which I remove the major portion of the asphalt before separating the oil into a light overhead fraction and a heavy residual fraction exhibiting a low viscosity temperature susceptibility I find that I may continue the distillation ofv the asphalt free oil until a still temperature of TOO-750 F. before any material. deterioration or impairment in the viscosity characteristics of the residual oil takes place.

As a preferred method of carrying out my invention Imay first dilute an asphaltic crude oil with alight hydrocarbon, solvent, such as liquid propane, in, the proportion of one part of the crude oil to six parts of the light hydrocarbon solvent. Separate the undissolved asphalt from the solvent solution of oil by simple decantation or filtration, and then separate the light fractions present in the substantially asphalt free oil from the heavy fractions by simple fractional distillation. In the absence of the asphalt, or most of the asphalt, Ifind it possible to carry the distillation to a still temperature of approximately 750 F.; or an on stream viscosity of 1200 seconds Saybolt Universal at 100 F. before any impairment takes place in the oil remaining in the still.

It is to be understood that the foregoing example is merely illustrative of one method of carrying out my process and is not to be construed as limiting the invention whichI claim.

I'claim:

1. A process for the production of lubricating oils from oil containing asphalt which comprises subjecting crude oil to a topping operation at a temperature not substantially in excess of 650 F. to remove the lighter fractions therefrom, separating most of the asphalt from the remaining residue and subsequently distilling the remain ing residue at a temperature not in excess of 750 F. to produce a lubricating oil distillate and; a residual undistilled lubricating oil, said last mentioned temperature being insufiicient to substantially impair the temperature viscosity susceptibility of said lubricating oil distillate and said residual undistilled lubricating oil.

,2. A process for the production of lubricating oilfromoils containing asphalt whichicomprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at F., separating most of the asphalt from the remaining residue and subsequently distilling the remaining residue at a temperature not exceeding 750 F. to produce a lubricating oil distillate and a residual undistilled lubricating oil, said temperature being insufficient to impair the temperature viscosity susceptibility of said lubricating oil distillate and said residual undistilled lubricating oil.

3. A process for the production of lubricating oil from oils containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., separating most of the asphalt from the remaining residue and subsequently distilling the remaining residue to an on stream viscosity not exceeding 1200 seconds Saybolt Universal at 100 to produce a lubricating oil distillate and a residual undistilled lubricating oil.

4. A process for the production of lubricating oil from oils containing asphalt which comprises subjecting crude oil to a topping operation at a temperature not substantially in excess of 650 F. to remove the lighter fractions therefrom, commingling the residue with an agent capable of removing substantially all of the asphalt from said residue, removing asphalt from said residue and subsequently distilling the remaining residue at a temperature not in excess of 750 F. to produce a lubricating oil distillate and a residual undistilled lubricating oil, said last mentioned temperature being insufficient to substantially impair the temperature viscosity susceptibility of said lubricating oil distillate and said residual undistilled lubricating oil.

5. A process for the production of lubricating oil from oils containing asphalt which comprises subjecting crude oil to a topping operation at a temperature not substantially in excess of 650 F. to remove the lighter fractions therefrom, commingling the residue with a solvent capable of dissolving the oil and precipitating the asphalt, separating the solvent solution of oil from the precipitated asphalt, separating the solvent from the oil and subsequently distilling said asphaltiree residue at a temperature not in excess of 750 F. to produce a lubricating oil distillate and a residual undistilled lubricating oil, said last mentioned temperature being insufficient to substantially impair the temperature viscosity susceptibility of said lubricating oil distillate and said residual undistilled lubricating oil.

6. A process as in claim 5 in which the solvent comprises a light liquid hydrocarbon.

'7. A process as in claim 5 in which the solvent comprises a liquefied normally gaseous hydrocarbon.

8. A process as in claim 5 in which the solvent comprises liquid propane.

9. A process for the production of lubricating oil from oil containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., separating substantially all of the asphalt from the residue and subsequently distilling the substantially asphalt-free residue at a temperature not in excess of substantially 750 F. to produce a lubricating oil distillate and a residual undistilled lubricating oil.

10. A process for the production of lubricating oil from oils containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., separating substantially all of the asphalt from the residue and subsequently distilling said asphalt-free residual oil to an on stream viscosity not exceeding 1200 seconds Saybolt Universal at 100 F. to produce overhead lubricating oil fractions and a residual undistilled lubricating oil.

11. A process for the production of lubricating oil from oils containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., commingling the residue with an agent capable of removing substantially all of the asphalt from said residue and removing the asphalt from said residue and subsequently distilling said asphalt-free residual oil to an on stream viscosity not exceeding 1200 seconds Saybolt Universal at 100 F.

12. A process for the production of lubricating oil from oils containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., commingling the residue with a solvent capable of dissolving the oil and precipitating the asphalt, separating the solvent solution of oil from the precipitated asphalt, separating the solvent from the oil and subsequently distilling said asphalt-free residual oil to an on stream viscosity not exceeding 1200 seconds S-aybolt Universal at 100 F.

13. A process for the production of lubricating oil from oil containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., commingling the residue with a liquefied normally gaseous hydrocarbon solvent to dissolve the oil and precipitate the asphalt, separating the solvent solution of oil from the precipitated asphalt, separating the solvent from the oil and subsequently distilling said asphalt-free residual oil to an on stream viscosity not exceeding 1200 seconds Saybolt Universal at 100 F.

14. A process for the production of lubricating oil from oils containing asphalt which comprises distilling crude oil to an on stream viscosity of approximately 500 seconds Saybolt Universal at 100 F., commingling the residue with liquid propane to dissolve the oil and precipitate the asphalt, separating the propane solution of oil from the precipitated asphalt, separating the propane from the oil and subsequently distilling said asphalt-free residual oil to an on stream viscosity not exceeding 1200 seconds Saybolt Universal at 100 F.

15. A process for the production of lubricating oil from oils containing asphalt which comprises separating substantially all of the asphalt contained in crude oil and subsequently subjecting the asphalt-free crude oil to a distillation at a temperature not in excess of 750 F. to produce lubricating oil distillates and a residual undistilled lubricating oil.

16. A process for the production of lubricating oil from oils containing asphalt which comprises commingling crude oil with an agent capable of removing substantially all of the asphalt from said crude oil, and subsequently distilling said asphalt-free oil to produce overhead lubricating oil fractions and a residual undistilled lubricating oil, said distillation being accomplished at a temperature not substantially in excess of 750 F.

17. A process for the production of lubricating oil from oils containing asphalt which comprises commingling crude oil with a light liquid hydrocarbon which is capable of dissolving the oil but not the asphalt, separating the undissolved asphalt from the solvent solution of oil, separating the solvent from the oil and subsequently distilling said asphalt-free oil to an on stream viscosity not exceeding 1200 seconds Saybolt Universal at 100 F. to produce lubricating oil distillates and an undistilled substantially asphaltfree residual oil.

gaseous hydrocarbon.

19. A process as in claim 17 in which the light liquid hydrocarbon comprises liquid propane.

ULRIC B. BRAY. 

